<template>
  <div class="containers">
    <div class="loading" v-if="loading">
        Loading...
    </div>
    <template v-else>
        <div class="canvas" ref="canvas"></div>
        <div id="js-properties-panel" class="panel"></div>
        <ul class="buttons">
           <li>
                <a ref="saveDiagram" href="javascript:" title="保存为bpmn">保存为bpmn</a>
            </li>
            <li>
                <a ref="saveSvg" href="javascript:" title="保存为svg">保存为svg</a>
            </li>
        </ul>
    </template>
  </div>
</template>

<script>
// 引入相关的依赖
import BpmnModeler from 'bpmn-js/lib/Modeler'
import axios from 'axios'
import { xmlStr } from '@/assets/xmlStr'
import propertiesProviderModule from 'bpmn-js-properties-panel/lib/provider/camunda'
export default {
  name: '',
  components: {},
  // 生命周期 - 创建完成（可以访问当前this实例）
  created () {},
  // 生命周期 - 载入后, Vue 实例挂载到实际的 DOM 操作完成，一般在该过程进行 Ajax 交互
  mounted () {
    this.init()
  },
  data () {
    return {
      // bpmn建模器
      bpmnModeler: null,
      container: null,
      canvas: null,
      loading: true,
      xmlUrl: '',
      defaultXmlStr: xmlStr
    }
  },
  // 方法集合
  methods: {
    async init () {
      this.loading = true
      this.xmlUrl = await this.getXmlUrl()
      this.loading = false
      this.$nextTick(() => {
        this.initBpmn()
      })
    },
    getXmlUrl () {
      return new Promise(resolve => {
        setTimeout(() => {
          const url = 'https://hexo-blog-1256114407.cos.ap-shenzhen-fsi.myqcloud.com/mock1.bpmn'
          resolve(url)
        }, 1000)
      })
    },
    initBpmn () {
      // 获取到属性ref为“canvas”的dom节点
      const canvas = this.$refs.canvas
      // 建模
      this.bpmnModeler = new BpmnModeler({
        container: canvas,
        // 添加控制板
        propertiesPanel: {
          parent: '#js-properties-panel'
        },
        additionalModules: [
          // 左边工具栏以及节点
          propertiesProviderModule
        ]
      })
      this.createNewDiagram()
    },
    async createNewDiagram () {
      const that = this
      let bpmnXmlStr = ''
      if (this.xmlUrl === '') {
        bpmnXmlStr = this.defaultXmlStr
        this.transformCanvas(bpmnXmlStr)
      } else {
        const res = await axios({
          method: 'get',
          timeout: 120000,
          url: that.xmlUrl,
          headers: { 'Content-Type': 'multipart/form-data' }
        })
        bpmnXmlStr = res.data
        this.transformCanvas(bpmnXmlStr)
      }
    },
    // 将字符串转换成图并渲染
    transformCanvas (bpmnXmlStr) {
      try {
        this.bpmnModeler.importXML(bpmnXmlStr)
        this.success()
        // 让图能自适应屏幕
        this.$nextTick(() => {
          var canvas = this.bpmnModeler.get('canvas')
          canvas.zoom('fit-viewport')
        })
      } catch (error) {
        console.log(error)
      }
    },
    success () {
      this.addBpmnListener()
      // this.addModelerListener()
    },
    // 添加绑定事件
    addBpmnListener () {
      const that = this
      // 获取a标签dom节点
      const downloadLink = this.$refs.saveDiagram
      const downloadSvgLink = this.$refs.saveSvg
      // 给图绑定事件，当图有发生改变就会触发这个事件
      this.bpmnModeler.on('commandStack.changed', function () {
        that.saveSVG(function (err, svg) {
          that.setEncoded(downloadSvgLink, 'diagram.svg', err ? null : svg)
        })
        that.saveDiagram(function (err, xml) {
          that.setEncoded(downloadLink, 'diagram.bpmn', err ? null : xml)
        })
      })
    },
    // 下载为SVG格式,done是个函数，调用的时候传入的
    saveSVG (done) {
      // 把传入的done再传给bpmn原型的saveSVG函数调用
      this.bpmnModeler.saveSVG(done)
    },
    // 下载为bpmn格式,done是个函数，调用的时候传入的
    saveDiagram (done) {
      // 把传入的done再传给bpmn原型的saveXML函数调用
      this.bpmnModeler.saveXML({ format: true }, function (err, xml) {
        done(err, xml)
      })
    },
    // 当图发生改变的时候会调用这个函数，这个data就是图的xml
    setEncoded (link, name, data) {
      // 把xml转换为URI，下载要用到的
      const encodedData = encodeURIComponent(data)
      // 下载图的具体操作,改变a的属性，className令a标签可点击，href令能下载，download是下载的文件的名字
      console.log(link, name, data)
      const xmlFile = new File([data], 'test.bpmn')
      console.log(xmlFile)
      if (data) {
        link.className = 'active'
        link.href = 'data:application/bpmn20-xml;charset=UTF-8,' + encodedData
        link.download = name
      }
    }
  },
  // 计算属性
  computed: {}
}
</script>

<style scoped>
.loading {
  font-size: 26px;
}
.containers{
  background-color: #ffffff;
  width: 100%;
  height: 100%;
  position: relative;
}
.canvas{
  width: 100%;
  height: 100%;
}
.panel{
  position: absolute;
  right: 0;
  top: 0;
  width: 300px;
}
.buttons {
  position: absolute;
  left: 20px;
  bottom: 20px;
}
.buttons li {
  display: inline-block;
  margin: 5px;
}
.buttons li a {
  color: #999;
  background: #eee;
  cursor: not-allowed;
  padding: 8px;
  border: 1px solid #ccc;
  text-decoration: none;
}
.buttons li a.active {
  color: #333;
  background: #fff;
  cursor: pointer;
}
</style>
